Shared Photo Streams not visible on new MacBook

I just used Setup Assistant to transfer everything from my old MacBook Pro to my new MacBook, and everything worked well EXCEPT that the several shared photo streams I've been part of didn't come over; i.e., I cannot see them in Photos. Sharing is turned on, and my iCloud Photos-related settings are correct, but no shared streams are visible. I'm using the latest version of Yosemite. Thanks for your help.